Cyrus' 70-date Best of Both Worlds concert tour sold out faster than you could say "Hannah Montana," leaving legions of screaming girls scrambling for tickets. In the last year, the 15-year-old also sold millions of CDs, signed a book deal and began filming a movie based on her Disney Channel series. She'll soon lend her voice to an animated canine comedy, Bolt.

The Celebrity 100 measures power, which boils down to two components: money and fame. Earnings estimates are for June 2007 - June 2008. We included income from endorsements, movies or other ventures only if the celebrity has been paid, applying the same rules to entertainment-related ventures. Management, agent and attorney's fees have not been deducted. Figures were rounded off where appropriate. Sources include Billboard, Pollstar, Adams Media Research, Nielsen SoundScan and Nielsen BookScan. How do we "calculate" fame? From Web hits on Google Blog Search, TV/Radio mentions on LexisNexis, overall press mentions on Factiva and the number of times a celebrity's image appeared on the cover of 55 consumer magazines.